Watch crystal



Oct. 15, 1929. P. B. DAVIS 1,731,712

WATCH CRYSTAL Filed Dec. 29, 1926 INVENTOR.

A TTORNEYS.

Patented Oct. 15, 1929 UNITED STATES PRIDHAM B. DAVIS, 01 LOS ANGELES,CALIFORNIA WATCH CRYSTAL Application filed December 29, 1926. Serial No.157,839.

This invention relates to articles of manufacture, and particularly towatch crystals of the non-breakable type. The average socallednon-breakable watch crystal is unsat isfactory in various particulars,the most notable of which is that the crystal under pressure willcontact with the hands or face of the watch.

My invention has for an object the provision of a non-breakable crystalwhich tends to greatly resist deformation.

Another object is the provision of a crystal which is inexpensive, easyto manufacture, and generally superior in use and service.

As best illustratin the invention, I have provided a sheet of drawing inwhich Figure 1 is a plan view of a wrist watch embodying the invention;

Figs. 2 and 3 are plan views of crystals of different contour embodyingthe invention;

Figure 4 is a cross section of the crystal shown in Fig. 2 and showingthe effect of pressure thereon; and,

Figure 5 is a perspective view of the crystal shown in Figure 2.

Corresponding parts in all the figures are designated by the samereference characters.

Referring to the drawing the improved article of manufacture in itsseveral forms is designated as an entirety by A and B and in Fig. 1 Ihave shown my improved article of manufacture in combination with awatch C. In particular the so-called unbreakable crystals are usuallyformed of some transparent material such as celluloid, and in thepresent instance I take the celluloid and form the same by a die in sucha manner that the resultant piece will assume a pyramidal form, asillustrated in Figs. 2, 4 and 5. It is important to note that the topzone 1 does not reach what may be termed a pointed apex. In other words,the respective sides 2 forming the pyramid merge together adjacent thetop 1 to provide a curved or domed portion. This is best illustrated inFig. 5. The division between the faces 2 is reasonably well defined, andwhile the faces may be comparatively fiat, yet it is within the purviewof the inven tion to have the outer surfaces slightly convex. Theoutline or rim portion of the crystal may assume any contour desired,depending upon the bezel of the watch. For instance, in Fig. 1 the bezel3 of the watch C is substantially square and the crystal A would fitwithin said bezel. If pressure were applied on the Zone 1 the crystalwould tend to move directly outwardly in all directions, as illustratedin Figure 4. However, if this crystal were placed within the bezel 3,the bezel would so confine the crystal that pres sure upon the part 1would not tend to deform the crystal unless the bezel was broken. In theso-called round or convex-concave watch crystals pressure upon thecenter of the crystal will cause such crystal to collapse downwardlyagainst the face of the watch or its hands, the expansion, due to suchcollap sion forcing the crystal upwardly around the central depressedportion, and often allowing the crystal to escape from its bezel. It isvery evident upon inspection of the drawing that this would bepractically impossible of accomplishment with the present invention.

In Figure 3, I provide a crystal B which retains all the features of myinvention in that it is of pyramidal form, the outline, however, beingslightly different in order that such a crystal may be applied to adifferent shaped bezel of a watch. As before, the pyramidal faces 4 and5 are provided, the faces 5 being larger than the faces 4. These facesall merge into a rounded or curved apex 6. This crystal would tend toresist stress the same as the crystal A.

This invention also contemplates the combination with a crystal of thebezel member which tends to aid the crystal in resisting deformation,such as illustrated in Figure 4. This bezel constitutes a reinforcement.

It is obvious that various changes and modifications may be made inpracticing the invention, in departure from the particular showing ofthe drawing, without departing from the true spirit of the invention.

Having thus disclosed my invention, I claim and desire to secure byLetters Patent:

1. As a new article of manufacture, apyramidal watch crystal formed ofunbreakable material.

2. As a new article of manufacture, a Watch crystal formed ofunbreakable material and having a plurality of joined triangular facesmerging in a curved apex.

3. As a new article of manufacture, a Watch crystal formed ofunbreakable material and having angularly related face portions. 7

In testimony whereof, I have signed my name to this specification.

PRIDHAM B. DAVIS.

